We proceed to the second article thus:

1. It seems that a man can will and do good without grace. For that of which he is master is within a man's power, and it was said previously that a man is master of his actions, especially of his willing. (Q.1, Art.1; Q.13, Art.6.) It follows that a man can will and do good by himself, without the help of grace.

2. Again, a man is master of what conforms with his nature more than of what is contrary to it. Now to sin is contrary to nature, as the Damascene says (2 De Fid. Orth.30), whereas the practice of virtue conforms with nature, as was said in Q.71, Art.1. It seems, therefore, that since a man can sin by himself, he can much more will and do good by himself.

3. Again, "truth is the good of the intellect," as the philosopher says in 6 Ethics 2. Now the intellect can know truth by itself, just as any other thing can perform its natural action by itself. Much more, then, can a man will and do good by himself.

On the other hand: the apostle says in Rom.9:16: "it is not of him that willeth, nor of him that runneth, but of God that sheweth mercy." Augustine, also, says that "men do absolutely nothing good without grace, whether by thought, will, love, or deed" (De Corrept. et Grat.2).

I answer: man's nature may be considered in two ways, either in its purity, as it was in our first parent before sin, or as corrupt, as it is in ourselves after the sin of our first parent. In either state, human nature needs divine help in order to do or to will any good, since it needs a first mover, as we said in the preceding article. In regard to the sufficiency of his operative power, man in the state of pure nature could will and do, by his own natural power, the good proportionate to his nature, such as the good of acquired virtue, though not surpassing good such as the good of infused virtue. In the state of corrupt nature he falls short of what nature makes possible, so that he cannot by his own power fulfil the whole good that pertains to his nature. Human nature is not so entirely corrupted by sin, however, as to be deprived of natural good altogether. Consequently, even in the state of corrupt nature a man can do some particular good by the power of his own nature, such as build houses, plant vineyards, and things of this kind. But he cannot achieve the whole good natural to him, as if he lacked nothing. One who is infirm, similarly, can make some movements by himself, but cannot move himself naturally like a man in health, unless cured by the help of medicine.

Thus in the state of pure nature man needs a power added to his natural power by grace, for one reason, namely, in order to do and to will supernatural good. But in the state of corrupt nature he needs this for two reasons, in order to be healed, and in order to achieve the meritorious good of supernatural virtue. In both states, moreover, he needs the divine help by which he is moved to act well.

On the first point: it is because of the deliberation of his reason, which can turn to one side or the other, that a man is master of his actions, and of willing and not willing. But although he is thus master, it is only through a previous deliberation that he either deliberates or does not deliberate. Since this regress cannot be infinite, we are finally driven to say that a man's free will is moved by an external principle higher than the mind of man, that is, by God. The philosopher indeed proves this in his chapter on Good Fortune (7 Mor. Eudem.18). Thus even the mind of a healthy man is not so thoroughly master of its actions that it does not need to be moved by God. Much more so the free will of a man weakened by sin and thereby hindered from good by the corruption of nature.

On the second point: to sin is nothing other than to fall short of the good which befits one according to one's nature. Now just as every created thing has its being from another, and considered in itself is nothing, so also it must be preserved by another in the good which befits its nature. It can nevertheless through itself fall short of this good, just as it can through itself cease to exist, if it is not providentially preserved.

On the third point: as we said in Art.1, a man cannot even know truth without divine help. Now his nature is impaired by sin more in the desire for good than in the knowledge of truth.